My tests have shown that "Fan NG" is rarely due to a defective fan! Rather, its cheap connector is responsible for this, as it loses contact with the pin on the motherboard over time and due to temperature fluctuations. This is especially noticeable with the blue cable, which transmits the signal of the fan control (or not, then see Fan NG). Here you can unplug the connector from the motherboard, clip the metal pins out of the connector with a fine slotted screwdriver and use a small pair of pliers to bend the very cheap metal back together a bit tighter so that it ultimately closes tighter around the pins of the motherboard again. Very simple solution to an insanely common problem.... Optionally, you could of course solder a standard fan connector on the motherboard and replace the fan accordingly, then should be even longer peace.

Sir Hindi me tres lete